Test clamp for test specimen



June 17, 1952 R. w. ROGERS ETAL TEST CLAMP FOR TEST SPECIMEN Filed June 18, 1.947

MKM

IN V EN TORS 0.66# 12K/Qa ATTORNEYS Patented June 17, 1952 TEST CLAMP FOR TEST SPECIMEN Robert W. Rogers, Barrington, R. I., and Samuel Reback, Fall River, Mass., assignors to Scott Testers, Inc., a corporation of Rhode Island Application June 18, 1947, Serial No. 755,530

3 Claims. (Cl. 24--248) 1 This invention relates to a clamp for gripping a specimen to be tested and more particularly to a clamp usually referred to as a toggle clamp.

Clamps of the character here referred to provide movable jaws which are each hung upon a pair of links to move in parallel relation as the jaw moves relative to the part to 'which the links are connected. The links cannot properly function at an angle higher than 20 to a perpendicular to the face of the jaws as the proper clamping action is not obtained. Thus, such a clamp has a very limited range as to the thickness of a specimen which may be received in the clamp. It is desirable that the links which mount the jaws be Iat approximately to a perpendicular to the jaws in order that the best gripping action at maximum pull may be provided for. It is also Ydesirable that the specimen clamped shall be on the center line of pull on the clamp in order that irregularities due to angular direction of pull may be minimized or eliminated.

One of the objects of this invention is to provide an adjustment for the jaws which will enable a single clamp to have a greater range ci capacity for engaging work of different thicknesses.

Another object of this invention is to provide a releasing means :for the jaws which will permit the jaws to be simultaneously moved away from gripping engagement with the work.

Another object of this invention is to provide an adjustment which may be calibrated and marked so that the jaws may be preset for different thicknesses or for different types of specimens.

Another object of this invention is to provide an arrangement for ejecting a specimen from the jaws when the jaws are moved to release the specimen.

Another object of this invention is to provide a guide for positioning the specimen between the gripping jaws.

Another object of this invention is to provide an arrangement so that the jaws may be opened by one hand of nthe operator.

With these and other objects in view, the invention consists of certain novel features of construction as will be more fully described and particularly pointed out in the appended claims.

In the accompanying drawings:

Fig. 1 is an elevation illustrating a pair of clamps and a specimen to be tested;

Fig. 2 is a perspective View of one of the clamps;

Fig. 3 is a perspective view of the gripping jaws 2 and the adjustable blocks which are movable in the clamp body;

Fig. 4 is a central sectional view through the clamp as shown in Fig. 2;

Fig. 5 is a sectional view taken substantially through the center of the jaws at right angles to the section shown in Fig. 4;

Fig. 6 is a section on substantially line t--S of Fig-4.

In proceeding with this invention, we provide a body of a general frame structure which has guide ways formed in it for directing the movement of a pair of blocks toward and from each other. Each of these blocks provides an anchor or mounting means for one of the gripping jaws for the work, the jaws being pivoted to the block by two pairs of parallelly arranged links. The arrangement is such that, when the work is gripped by the jaws, the links will be at an angle to a perpendicular to the face of the jaws so that, as pull occurs on the jaws, the jaws will tend to swing the links and will move toward each other into irmer gripping relation. The blocks are adjustably mounted yin the body so a different spaced relation of the jaws may occur, the adjustment being by means of holes and a pin so set that the pin can enter holes that are in registry when in but a certain definite position which is known and which may be calibrated for diiierent sizes or characteristics of different specimens. Each of the jaws may be provided with an ejecting pin, and the jaws may be equipped with a means so that through a single handle both jaws are moved togetherV by. one hand of the operator. Guides for positioning the work may be conveniently positioned in the clamp.

With reference to the drawings, the body of the clamp is designated generally i0 and comprises a pair lof plates Il and i2 which are supported in spaced relation by means of spacing members I3 placed along the longitudinal edges of the plates H and l2 and provide with the plates ll and l2 guidesv I4 vfor directing the movement of blocks Iii in the body, that is, the inner surfaces I6 of the members I3 will form back and front guiding surfaces, while the inner surface Il of the plate Il and the inner surface i8 of the plate l2 will provide top and bottom guiding surfaces,

Each of the blocks is provided with a plurality of openings I9, while the plates l l and I2'are provided with a plurality of openings 20. The openings 20 are angularly arranged with reference to the guided direction of movement oi the block and are so staggered that but one hole will register with a hole I9 in the block. Thus, when the aeodees pin is in one hole, the block will be at one definite position with relation to the body and when in another hole will be at another definite position with relation to the body along the guide; and, thus, there may be had a calibration so that different holes may be used for different thicknesses of specimens. A pin 2| will beinserted through the holes in the plates I I and I2 and through the block for this purpose and may have an anchoring chain 22 for attaching the same to the clamp. The plates I I and I2 will have central openings 23 and 24 in alignment for positioning the speci; men in the clamp; and, above thewopen'ing 23, there will be provided an attachingbridge 25 (iom-i prising a horizontal plate 26 and two` inclined plates 2l spacing the plate 25 a distance above the plate I I. A boss 28 is provided on this plate 26 having a threaded socket 29 for the reception of an attaching rod 30 upon which pull, or' resistance to pull on the other end of the specimen, may be applied. The under surface y3| of this bridge may serve as a means for limiting' or guiding-one end of the specimen into a desired position between the clamping jaws.'

The clamping jaws are designated 32 .and consist of a T-block 33 having a separable face' member 34 with serrationsthereon which may be attached by means of screws 35 to the block 33.` VA spring-pressed pin 36 is slidable in the jaw and facing member and is pressed by a spring 38 outwardly and is limited in its movement by the facing member 34 engaging the shoulderY formed by the head 31 on the pin 36.V Each of these jaws 32 is attached to one of the bloeks I5 by links 49 and 4I arranged in parallel relation and pivoted as at 42 and 43 to the block and as at 44 and 45 to the jaw. These parallelly arrangedlinks are provided both at the front and back edgefof the jaws and blocks. One of the pivots comprises a shaft 45 (see Fig. 3) which passes through one of the blocks and has its link such as 4I fixed to the shaft. This shaftjs also provided witha lever 41 acting as a handle which is secured in place on theshaft by a nut 48 so that movement of this lever to different positions will serve to swing the link 4I and by reason of the connection above mentioned also the link 40 to move the jaw toward and from a center line through the clamp. Inorder that both jaws may be moved at the same time, we provide a bar 49 seured to the jaw which is equipped with the handle as by means of a-screw 50 which bar is slidably related to the' other jaw in guides 5I so that as one jaw is raised the other jaw will also be' raised and thus will swing toward and from the center of the clamp a like amount. This bar also' has a means for limiting the insertion of the work between the jaws by acting as a back guide in instances .where desired.

From the above it will be apparent that we have provided a pair of jaws Vwhich will remain centralized with Vreference to thepull rod 30 at all times lif the blocks which carry them are adjusted to equal positions from the center line.

'I he blocks may be adjusted in srnallierements and held there by reason ofv the particular arrangement of the holes whichis provided. In fact, the adjustment may be had between centralizing positions by adjusting one .block while leaving the other `block fixed although the center of pull will be slightly off in such case. When it is desired to release the jaws from gripping position which they will assume as the work is pulled, it is merely necessary to move the handle 41 by one hand for lifting the jaws, as in Fig. 1, and releasing the work. As the work is released, the spring pins 36 will veject the work from the jaws. .i

A spring 55 urges the lever in av direetion to cause the jaws to close so that after the work is inserted release of the handle will permit the spring 55 to move the jaws so as to grip the work.

We claim:

1. A clamp for gripping a specimen subjected to a pulling forc'effor testing or the like comprising lhollow body having sides, top, and bottom walls, said top and bottom walls having aligned openings therethrough through which the said specimen may be passed, a pair of blocks slidably guided in said body by' said walls on opposite sides of-said openings, a pair of gripping jaws within said body and out of engagement with saidbody and having opposite flat surfaces for engaging the specimen, a pair o f parallelly arranged links on oppositesides of each block for movabl-y mounting each jaw on a block for suspension therefrom only by said links and for parallel motion of said jaws to and from each other',said links and said blocks' being so related that the links extend at an acute vangle to the gripping face of the jaws to cause the jaws to move-toward each other aspull is exerted on the specimen, a shaft to which one of said links is fixed for p-vot'i` ally mounting the link, a handle Xed to said shaft for moving vthe jaws from each other, and

spring means for moving said jaws towards each other.

2. A clamp as in claim l wherein a pluralityl of parallel rows of holes are provided in the body and a plurality of parallel rows of holes are in the block and with the rows of holes in said body extending at an angle to the rows of holes in said block so that one hole in the block will only reg!" ister with one hole inthe body whereby a denite size relation less than the distance between said rows may be provided.

3. A clamp as in claim 1 wherein a bar is flied to one of said jaws and slidably related to the other of said jaws whereby said jaws are roved together by said handle'` v ROBERT w, ROGERS. SAMUEL REBACK.

REFERENCES CITED The following Areferences are of record ln the file of this patent:

UNITED STATES PA'rEiITs Number o I 

